Intradiscal pressure change induced by a lumbar orthosis

Pathologies rachidiennes (I) / Revue d’E´pide´miologie et de Sante´ Publique 55S (2012) e274–e280 Materials/patients and methods.– Posturographic recordings of five subjects with IS (age = [13.4  2.3 years], size = [1.58  0.1 m], Cobb’s angle = [26.5  3.58]) were performed by using a Satel platform (t = 51.2 s, Fs = 40 Hz). The lateral oscillations in unstable conditions, closed eyes, with corset were observed. The raw data of the sensors were exported to be analyzed by using the data processing software IGOR (version 6.0). The method of ‘‘zero-filling’’ is usually used to improve the definition of FFT, but the convolution of the FFT of the signal with the FFT of a rectangular function disrupts the reading. To reduce this disruption, we apply the analytical methods used in such fields as Raman spectroscopy. Results.– The Fourier transform that we have calculated can decompose the signal into a Fourier series consisting of about ten oscillations on the domain (0.08 Hz; 0.5 Hz). The predominant ones are around 0.1 Hz. Discussion.– This method is used to improve the definition and usually delicate interpretation of FFT. Under the experimental conditions in place, we bring to light the existence of frequency peaks which are well individualized and at around 0.1 Hz. These peaks seem to correspond to the spinal disturbance caused by the wearing of corsets and thus to the absence of postural adjustment of this zone when the IS subject is placed under the conditions of instability. References [1] Nault ML, Allard P, Hinse S, Le Blanc, Caron O, Labelle H, Sadeghi H. relations between standing stability and body posture parameters in adolescent idiopathic scoliosis. Spine 2002;27(17):1911–7. [2] Haumont T, Gauchard GC, Lascombes P, Perrin PP. Spine 2011; 36(13):847–54. http://dx.doi.org/10.1016/j.rehab.2012.07.703 CO22-006-e

Cephalic stabilization and idiopathic scoliosis M.-A. Guyot *, J.-F. Catanzariti, M.-O. Agnani, C. Donze´, S. Demaille Service de MPRF-GHICL, 115, rue du Grand-But, 59462 Lomme, France *Corresponding author. E-mail address: [email protected]. Keywords: Idiopathic scoliosis; Cephalic repositioning; Cervical Proprioception Introduction.– In idiopathic scoliosis (IS), increase of osteopontin tissue expression [1] due to a defect of melatonin signaling could explain the various oculomotor, vestibular and proprioceptive anomalies. These anomalies can disturb postural control including cephalic stabilization control. Cephalic stabilization is influenced by vestibular, visual, oculomotor, proprioceptive and cervical information and used as a reference to vertical gravity. Objective.– To evaluate the cephalic stabilization in IS, with a validated test: Cephalic Repositioning Test (CRT). Methods and materials.– In this prospective study, we evaluate, in a IS population with an angle Cobb  158, cephalic repositioning ability with CRT on a target, eyes closed, after ten right rotation and ten left rotations. Quantitative and qualitative statistical analysis is performed. Results.– Thirteen IS subjects (age 13.5  2.36) were evaluated. Forty percent have a pathological right and left CRT (> 68), 76.9% have at least one pathological CRT and 61.1% have a pathological left CRT. Higher right lateralization was found significantly after repositioning. Abnormal left CRT is associated with a high angle Cobb lumbar (P < 0.05), and more significant with left convexity lumbar scoliosis (P < 0.05). Discussion and conclusion.– These preliminary results show a disturbance of CRT and indirectly proprioceptive cervical control in IS. Requires further evaluation with a larger number of IS and matched a control group. In this disease, the test systematization is the detection and guidance to a specific rehabilitation: oculo-cervical reprogramming according to Revel’s [2] protocol. Références [1] Lombardi G, Akoume MY, Colombini A, Moreau A, Banfi G. Biochemistry of adolescent idiopathic scoliosis. Adv Clin Chem 2011;54:165–82. [2] Revel M, Minguet M, Gergoy P, et al. Changes in cervicocephalic kinesthesia after a proprioceptive rehabilitation program in patients with neck pain: a randomized controlled study. Arch Phys Med Rehabil 1994; 75:895–9. http://dx.doi.org/10.1016/j.rehab.2012.07.704

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Laterality and idiopathic scoliosis J.-F. Catanzariti *, M.-M. Guyot, M.-O. Agnani, C. Donze, S. Demaille Ghicl-hoˆpital Saint-Philibert, rue du Grand-But, 59462 Lomme, France *Corresponding author. E-mail address: [email protected]. Keywords: Idiopathic scoliosis; Laterality; Melatonin; Posture; Interhemispheric interaction Introduction.– Several authors found a significant relation between handedness and asymmetry of trunk. The laterality is partially in relation with interhemispheric interaction. It is permitted by interhemispheric commisura, particularly the corpus callosum. Arguments evoke relation between abnormalities of the interhemispheric interaction and scoliosis: 1) the HGPPS, rare human syndrome, associates scoliosis with dysfunction of commissural neurons; 2) significant decrease of the volume of the corpus callosum in the idiopathic scoliosis (IS). Objective.– Evaluate the interhemispheric interaction in IS, by studying eyeshand-foot laterality. Methods and materials.– Prospective case-control study, estimating by eyehand-foot laterality with specific tests, to SI  158. The score allows classifying each laterality in right or left dominance. When the three dominances are ispilateral, the laterality is homogeneous; in the opposite, it’s a crossdominance. Results.– Two groups were estimated: 38 AIS, and 26 controls. AIS present more cross-dominance than controls: 69% vs 30% (P = 0,003). Crossdominance eye-hand is most frequent (eye-hand 65,4%; foot-hand 11,5%; mixed dominance 23,1%). These observations show disturbance of the interhemispheric interaction. Discussion and conclusion.– Results are independent from the scoliotic deformation, because dominance install before seven years. The crossdominance eye-hand favors direct retino-geniculo-cortical pathway, to save time of interhemispheric transfer during eyes-hand activities. This preferential use of some visual pathways can be secondary of the defect of melatonin signal transduction in ISA. This defect induces increase of osteopontin’s tissular expression. Osteopontin, coupled with the CD44 receptor, which can inhibit, in the optic chiasm, the growth of visual axons in some directions. The sub-use of the crossed retino-tecto-cortical pathway, which contributes to the cervicocephalic visual stabilization, could perturb the postural downward control. The incapacity of proprioceptive compensation, especially cervical, could explain the abnormal muscular adaptation of trunk, and consequently spine deformity. These results can generate new therapeutic orientations. Further reading Shi L, Wang D, Chu WC, Burwell RG, Freeman BJ, Heng PA, Cheng JC. Volume-based morphometry of brain MR images in adolescent idiopathic scoliosis and healthy control subjects. AJNR Am J Neuroradiol 2009;30(7):1302–7. Lombardi G, Akoume MY, Colombini A, Moreau A, Banfi G. Biochemistry of adolescent idiopathic scoliosis. Adv Clin Chem 2011;54:165–82. http://dx.doi.org/10.1016/j.rehab.2012.07.705

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Intradiscal pressure change induced by a lumbar orthosis M.-F. Munoz a,*, J.-F. Salmochi b, P. Badel c, P. Rougier d, P. Calmels d, J. Molimard c, S. Avril c a Centre inge´nierie sante´, e´cole des mines de Saint-E´tienne, 158, cours Fauriel, 42023 Saint-E´tienne cedex 2, France b Clinique du Parc, Lyon, France c Centre inge´nierie sante´, e´cole des Mines de Saint-E´tienne, France d Laboratoire de physiologie de l’exercice, universite´ de Saint-E´tienne, France *Corresponding author. E-mail address: [email protected]. Keywords: Lumbar orthosis; Intradiscal pressure; Finite element; Low back pain

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Introduction.– To correct the spine sagittal imbalance, lumbar orthoses are commonly prescribed as conservative treatment of low back pain. These devices could affect the distribution of loads among passive and active lumbar subsystems. However, with only one study in this field proposed by Nachemson et al (1983), their biomechanical action such as the reduction of the intradiscal pressure (IDP) remains unknown and controversial. The goal of this study was to investigate the IDP change induced by a rigid lumbar orthosis from a new non-invasive measurement method. Method.– From the comparison of two radiographs EOSTM (Biospace, Paris) with and without a lumbar orthosis, the displacements and rotations of each vertebra were calculated and implemented in a patient-specific finite element modelling. The IDP measurements along each lumbar disc were extracted with a precision of  2.5 Pa. Twenty patients were tested in standing or sitting posture with a semi-rigid lumbar orthosis LordactivTM (Ormihl-Danet, Villeurbanne) in two conditions: with or without a curved rigid lumbar part. Result.– A curved rigid lumbar part was necessary to obtain significant IDP distribution change along the anteroposterior direction. Interestingly, an IDP decrease appeared in some patients until –50 Pa. However, the IDP change appeared very posture, disc level and patient-dependent ranging from –50 to +8 Pa. Discussion.– An IDP distribution change reveals a different load sharing between posterior elements and intervertebral discs whereas decompression only could be explained by a decrease muscle activity. Especially, the intradiscal elasticity (age-dependent) and the lumbar back adipose tissue thickness are the main variables correlated with the interindividual differences. Conclusion.– These results demonstrated that wearing a rigid lumbar orthosis can significantly influence the stress-strain values in diseased discs, provided that the patient is kept an sufficient elasticity. Further reading Nachemson A., Schultz A., Andersson G., 1983. Mechanical effectiveness studies of lumbar spine orthoses. Scand J Rehabil Med Suppl;9: p. 139–49. http://dx.doi.org/10.1016/j.rehab.2012.07.706

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New non-invasive and patient-specific method allowing intradiscal pressure change measurement induced by lumbar conservative or surgical treatments M.-F. Munoz a,*, J.-F. Salmochi b, P. Rougier c, P. Calmels d, P. Badel e, J. Molimard e, S. Avril e a Centre inge´nierie sante´, e´cole des Mines de Saint-E´tienne, 158, cours Fauriel, 42023 Saint-E´tienne cedex 2, France

b

Clinique du Parc, Lyon, France Laboratoire de physiologie de l’exercice, universite´ de Savoie, France d Laboratoire de physiologie de l’exercice, universite´ de Saint-E´tienne, France e Centre inge´nierie sante´, e´cole des Mines de Saint-E´tienne, France *Auteur correspondant. E-mail address: [email protected]. c

Keywords: Intervertebral disc; Pressure; Load; Finite element; Low back pain Introduction.– Mechanical loads on the spine appear to play a major role in the etiology of low back pain. Unfortunately, little is known about the intradiscal pressure change associated with conservative or surgical treatments. Direct and indirect measurements are mainly limited respectively by the invasiveness and by the patient-specific calibration of the finite element modelling. The goal of this study was to develop a new non-invasive and patient-specific method allowing lumbar intradiscal pressure change measurement induced by conservative or surgical treatments. Method.– According to an adaptation of the Catmull-Rom Splines method validated by McCane et al. (2006), the displacements and rotations of each vertebra were measured from the comparison of two radiographs EOSTM (Biospace, Paris) before and after treatment. The elastic modulus of each disc was calibrated from the comparison of two radiographs non-loaded and loaded with 4 kg on each shoulder of the patient. A finite element model was created from the radiograph without treatment. Finally, the kinematic of each vertebra and the elastic modulus of each disc were implemented in this model, from which the pressure measurements along each lumbar disc were extracted. To determine the precision of this method, the accuracy of  0.78 and  0.285 mm reported by McCane et al. (2006) for the kinematic measurement was simulated in the model created from a clinical case. Results.– The mean intradiscal pressure precision measured along the disc was  2.5 Pa. Discussion.– The precision appeared sufficient to measure a clinically relevant change of pressure in the lumbar disc after treatment. The main advantages of this method are the inclusion of the differences of geometry and elasticity between each level of the lumbar disc and for each patient. Thus, the effectiveness of the treatment can be interpreted in light of the remaining level of discal elasticity. Conclusion.– This method could help to measure effective intradiscal pressure to better understand and improve conservative or surgical treatments of low back pain. Further reading McCane B., King T.I., Abbott J.H., 2006. Calculating the 2-D motion of lumbar vertebrae using splines. Journal of Biomechanics;39: p. 2703–08. http://dx.doi.org/10.1016/j.rehab.2012.07.707